This invention relates in general to electronic stability control systems and more particularly to improving the performance of electronic stability control systems with the use of static tire parameters.
All vehicle tires are not alike. They come in many different diameters, widths, and profiles. They have variations in construction, such as the use of aramid fiber or steel reinforcement belts, different sidewall thicknesses, and so forth that cause different tires to respond differently when a load is imposed on the tire. Vehicle performance is affected by the type of tires that are put on a vehicle. To ensure that a tire of the proper construction and performance for the vehicle is installed, it is known to put identifying markings on a tire. For example, a tire may be provided with a marking like “P215/65 R15 89H”. The “P” indicates that the tire is for a passenger car. The “215” indicates the tire width in millimeters from sidewall to sidewall. The “65” indicates the aspect ratio of the tire sidewall measurement to the tire height; therefore “65” indicates the ratio equals 65%. The “R” indicates the type of tire construction; in this case, the tire is a Radial tire. The “15” indicates the wheel diameter or the measurement of the wheel's rim. This tire is adapted to fit on a 15 inch rim. The “89H” indicates a load index and speed rating. Thus, “89H” represents the load index minus the amount of weight the tire can safely carry when properly inflated. “H” is the speed rating. “H” indicates that the tire is rated for speeds up to 130 MPH (miles per hour). Other examples of speed ratings are: Q=100 MPH, S=112 MPH, U=124 MPH, H=130 MPH, Z=149 MPH and higher. Other information on a tire is the tire construction, the Uniform Tire Quality Grading (UTQG), and the maximum cold inflation pressure and load.
Additionally, it has been proposed by one manufacturer to provide each tire with a Radio Frequency Identification (RFID) tag for tire tracking in compliance with the United States Transportation, Recall, Enhancement, Accountability and Documentation Act (TREAD Act). RFID is an electronic identification method in which data is stored, and can be remotely retrieved from devices called RFID tags or transponders. An RFID tag can be attached to or incorporated into a product or even an animal. RFID tags contain silicon chips and antennas to enable them to receive and respond to radio-frequency queries from an RFID transceiver. Passive tags require no internal power source, whereas active tags require a power source.
Using RFID tag on tires for the purposes of identifying and tracking the tires during manufacture, and distribution for the purposes of the TREAD Act would involve communication with the RFID while the tire is at rest to obtain data identifying the particular tire.
As previously indicated, not all tires are alike. When purchasing a vehicle, a customer typically has a choice of wheels and associated tires which can be ordered with a vehicle, with each different choice typically having some consequence in the handling of a vehicle. For example, in a Sport Utility Vehicle (SUV) tires with a fairly large difference in diameter are available to the purchaser. One purchaser may choose large diameter tires for improved ground clearance when driving off road. Another purchaser may choose tires with a smaller diameter, resulting in a lower center of gravity and better stability for the vehicle.
Various electronic stability control systems are known which utilize information from various sensors that measure dynamic characteristics of the movement of a vehicle, such as acceleration, yaw rate, pitch rate, roll rate, steering angle, vehicle braking action, vehicle drive train operation, etc., to control operation of various components of the vehicle, to improve handling. Examples of components which may be controlled by the electronic stability control system are actuators coupled to the vehicle suspension system, the engine/powertrain, steering actuators, and the vehicle brakes. These systems have typically been designed in the past around a nominal tire design, and the manufacturer will specify the use of certain tires having performance within certain limits of the nominal tire design, so that the stability of the vehicle will lie within accepted norms, regardless of which of the factory specified option tires are chosen by a consumer.